Structures, Thermochemical Properties, and Bonding of Mixed Alkaline-Earth-Metal Silicon Trimers Si3M+/0/– with M = Be, Mg, Ca

An ab initio investigation of the adsorption properties of water on binary AlSi clusters

Nanoalloys represent potential catalysts for the water splitting reaction. The water–cluster interaction is a key aspect of the process, but is not fully understood. This work provides an in-depth study and insights into the AlxSiy·H₂O case.

Mechanistic Study on Water Splitting Reactions by Small Silicon Clusters Si3X, X = Si, Be, Mg, Ca

Interaction, dissociation, and dehydrogenation reactions of water monomer and dimer with pure and mixed tetrameric silicon clusters Si₃X with X = Si, Be, Mg, Ca were investigated using high accuracy quantum chemical calculations. While geometries were optimized using the DFT/B3LYP functional with the aug-cc-pVTZ basis set, reaction energy profiles were constructed making use of the coupled-cluster theory with extrapolation to complete basis set, CCSD(T)/CBS. Cleavage of the O-H bond in water dimer is found to be more favored than that of water monomer in the reaction with Si₄. The water acceptor monomer in water dimer performs as an internal catalyst facilitating H atom transfer to form H₂. Adsorption of water dimer on Si₃X clusters mostly takes place upon interaction of the donor water molecule with Si cluster. Water dimer adsorbs more strongly on Si₃M than on Si₄. The most stable complexes obtained upon interaction of water dimer with Si₃M mainly arise from M-O interaction in preference over a Si-O connection. Substitution of a Si atom in Si₄ by an earth alkaline metal induces a substantial reduction of the energy barrier for the (rate-limiting) first O-H bond cleavage of water dimer. The most remarkable achievement upon doping is a disappearance of the overall energy barrier for the initial O-H bond cleavage in water dimer. Of the three binary Si₃M clusters considered, dehydrogenation of water dimer driven by Si₃Be is the most kinetically and thermodynamically favorable pathway. In comparison to another cluster such as Al₆ and nanoparticles Ru₅₅, energy barriers for water dimer dissociation on Si₃M are much lower. The mixed clusters Si₃M turn out to be as efficient alternative reagents for O-H dissociation and hydrogen production from water dimer. This study proposes further searches for other mixed silicon clusters as realistic gas phase reagents for crucial dehydrogenation processes in such a way they can be prepared and conducted in experiment.

Structural assignment, and electronic and magnetic properties of lanthanide metal doped silicon heptamers Si7M0/− with M = Pr, Gd and Ho

The ground state geometries of neutral and anionic lanthanide-metal-doped silicon clusters Si₇M^0/− with M = Pr, Gd and Ho were determined by quantum chemical (DFT) computations and the previous experimental photoelectron spectra were assigned.